Machines for forming a workpiece between two ram heads

ABSTRACT

Improved hydraulic forming and forging presses for combined operation, in which there are valving facilities and piston and cylinder arrangements enabling various combinations of relative movement and rates of movement of the rams to be adjusted, in accordance with the kind of metal-forming operations which are to be effected.

United States Patent 1191 Briiuer 1451 Jan. 2, 1973 s41 MACHINES FOR FORMING A 962,705 6/1910 Fielding ..72/453 WORKPIECE BETWEEN TWO RAM 2,409,254 10/1946 Conzelman ..72/453 3,105,414 10/1963 Cvjetkovic ..91/172 HEADS 3 173 286 3/1965 D' hl 72/453 1sc er Inventor: Willi i g. G y 3,130,129 4/1965 Riemenschneider.. .72/453 3,209,578 10/1965 Muller .72/407 [73] Ass'gnee' i??? g 3,336,788 8/1967 OlteSlad ..72/453 1 "many 3,353,396 11/1967 Brauer ..72/453 22 i d; 24 1971 3,429,174 2/1969 Fracke ..72/453 [21] Appl. No.: 118,528 FOREIGN PATENTS OR APPLICATIONS R l t d Us. A li m D t 68,363 5/1940 Czechoslovakia ..72/453 [63] Contijnuatfijon of Ser. No. 764,901, Oct. 3, 1968, primary Examiner charles Assistant Examiner-Gene P. Crosby [30] Foreign Application Priority Data Attorneyfnolman and Stem Oct. 9, 1967 Austria ..9134 [57] ABSTRACT Improved hydraulic forming and forging presses for g combined operation, in which there are valving facili ties and piston and cylinder arrangements enabling [58] Field of Search 100/269 R various combinations of relative movement and rates of movement of the rams to be adjusted, in ac- [56] References cued cordance with the kind of metal-forming operations UNITED STATES PATENTS which are to be effected.

352,314 11/1886 Hainsworth ..72/453 7 Claims, 2 Drawing Figures MACHINES FOR FORMING A WORKPIECE BETWEEN TWO RAM HEADS This application is a continuation of application Ser. No. 764,901 filed Oct. 3, 1968, now abandoned.

BACKGROUND OF THE INVENTION the extension cylinder space acts upon pistons.

- When forming a workpiece between two ram heads, the two heads press against the workpiece. There are two methods known by which a workpiece can be shaped in this fashion. One method is forging and the other is press-forming. In a forging operation, a ram head or hammer transfers impact energy to the workpiece and the degree of deformation of the workpiece is dependent upon the amount of impact energy involved. The deformation or shaping in this kind of operation, is carried out in a relatively short time. In press-forming, a ram exerts a pressure on the workpiece and the degree of deformation or shaping thereof as a consequence of the ram travel, is dependent upon the press force exerted. The deformation of the workpiece is thus a factor which can be influenced not simply by whether or not a press-forming or a forging operation is used, but also by the application of varying degrees of press-forming force or varying degrees of impact energy. Each of these possible controls on the operation of forming, is a factor which may be included in a machine for forming a workpiece between two ram heads. Amachine of this kind, which will be referred to in the following as a forming machine, and which has many possible applications, is particularly useful in situations where none of the forming facilities is used frequently and many different forming facilities are required.

One quite generally known forming machine is what will be referred to subsequently as a single press. In single presses, one of the two rams is fixed and the other movable in relation to the workpiece, for the purpose of pressing the latter. The maximum press load in a single press is unlimited as far as practical requirements are concerned. The disadvantage of this kind of press, however, is that it is not very versatile in application since it cannot perform any forging-type operations.

Another forming machine, known for example .from the German Pat. specification No. 974,854, will be referred to subsequently as a single hammer. In the case of the single hammer, once again one of the two rams is fixed and the other moves and strikes against the workpiece. The field of possible applications of the single hammer is unfortunately limited not only by the fact that it cannot carry out any pressing operations, but also by the fact that there is a practical limit upon its maximum" impact energy. Again, French specification No. 1,293,323 for example, German specification No. 1,116,510 or VDI-Nachrichten of the 24th Oct. 1962, page 12, all disclose a forming machine which employs twin hammers. In the twin hammer 5 operations.

Also known for example, from German specification No. 876,796, is what is termed a single hammer press. In the single hammer press, in shaping or deforming a workpiece one of the two rams is fixed and the other is moved in relation to the workpiece. The workpiece is either struck (forged) or pressed by the moving ram. The field of application of the single hammer press, however, is again limited because the maximum impact energy that this device can provide is limited by practical considerations, just as in the case of the single hammer machine. This is a drawback not only because it limits the field of application of single hammer presses, but also because a design which is suitable for a high press force, so that a wide variety of pressing applications is offered, is ill-suited to forging operations. It is therefore regarded as uneconomical to create a versatile forming machine by designing a single hammer press for high press loadings.

SUMMARY OF THE INVENTION The present invention has as its object a machine of the kind referred to above, which is characterized in that provision is made for a mutual opposing movement of each of the rams in extension and retraction directions as well as for engagement of pistons delimiting the return cylinder space and an impact cylinder space, with the rams, at least one of the two rams additionally being associated with a press cylinder space delimited by a piston engaging said ram and associated with supply facilities for the introduction of pressurized fluid. In the machine in accordance with the invention, one cylinder space, to which a pressurized medium is supplied which produces a hammer blow, is designated the impact cylinder space. Correspondingly, the press cylinder space is supplied with the pressurized medium which produces a pressure stroke of the ram, and the return cylinder space is supplied with the pressurized fluid which causes the rams to retract.

The object of the present invention is a forming machine which not only is more versatile in application than the known forming machines, but which enables the additional applications to be achieved in an economical way. The forming machine in accordance with the invention is a twin hammer press which can be operated arbitrarily as a twin hammer (forging) machine and as a press. It is designed to produce either a high impact energy or a high press force, and the essentials of its design for high press force can also be exploited in a forging context.

In one embodiment of the machine in accordance with the invention, the two rams are moved in opposition to one another in forging operations, but not in pressing operations. An embodiment of this kind, operating as a single press, is obtained when the hammer blow cylinder space is provided in association with one of the rams and the piston delimiting this space arranged to engage with the other ram. The piston delimiting the press cylinder space to which pressurized fluid is'supplied, engages with the ram associated with the hammer blow cylinder space. During a press stroke, there is no pressurized fluid in the hammer blow cylinder space. A piston delimiting the return cylinder space is supplied with pressurized fluid medium and likewise engages the ram associated with the hammer blow cylinder space. Pressing is carried out against the force of the pressurized medium in the return cylinder space. This embodiment is a further development, in accordance with the present invention, of the twin hammer design disclosed by VDI- Nachrichten,'24th Oct. 1962, page 12.

A machine in accordance with the invention is preferably equipped with a control facility in which the return cylinder space is connected with an extension valve device. The extension valve device will include an impact valve and a travel valve for slowly moving the two rams towards each other. The supply to the return cylinder space will be via a check valve and that to the press cylinder space via a press valve. The impact valve has a large flow cross-section and is designed, for example, in the manner disclosed in German specification No. 974,854 in relation to a drop-hammer. The travel valve will have a variable, small flow cross-section and serves to slowly move the two rams together, and is open during pressing operations. During forging and press-forming, the extension movement of the rams displaces fluid out of one of the return cylinder spaces through the open impact valve and the open travel valve.

In order to return the rams, the extension valve device is closed, the press valve closed and the return valve opened. The opening of the latter valve, causes pressurized fluid to be supplied to one of the return cylinder spaces. For producing a press feed movement of the rams, the travel valve is opened, the press valve opened and the return valve shut. With the press valve open, pressurized fluid is fed into the press cylinder space and fluid escapes from the return cylinder space through the open travel valve. For hammer blow movement of the ram, the impact valve is opened and the return valve closed. Fluid leaves the return cylinder space through the open impact valve.

In one embodiment of the machine in accordance with the invention, facility is provided for supplying pressurized fluid or gas to the impact cylinder space. However, a preferred embodiment is one in which with the rams retracted, a closed-off pressure chamber surrounding the impact cylinder space is filled with compressed, high-pressure gas. In this machine, impact is produced not by the supply of pressurized fluid or gas to an impact cylinder space, but by the pressure of the gas compressed (preferably by the return motion of the rams) in the closed-off pressure or compression chamber.

In a preferred embodiment, the rams are moved in opposition during press-forming operations as well, so that a means used only during press-forming operations in order to hold one ram stationary, is no longer needed and the installed height of the machine is reduced as a consequence. In this context, it is advantageous if one of the two rams is heavier by a number of times than the other, with the heavier ram moving correspondingly slower than the lighter one during forging operations. This preferred embodiment may conveniently be further developed to the point where there is a positive hydraulic coupling between the two rams.

Using this hydraulic coupling facility, the two rams can be made to move synchronously in opposition to one another not only during retraction, but also in forging operations and when executing a press stroke.

The invention will now be described with reference to the accompanying drawings which illustrate two embodiments of the invention but in no restrictive sense.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a section through a machine according to the invention operating as a single press; and

FIG. 2 illustrates a section through a machine according to the invention operating as a twin press.

DETAILED DESCRIPTION OF THE INVENTION The two machines illustrated operate in a vertical position and in each case incorporate two rams 1, 2 arranged in line one above the other. The two rams l, 2 are movable in relation to one another, in a frame 3. The bottom ram 2 is preferably several times heavier than the upper ram 1 and accordingly travels a shorter distance than said upper ram. This is a convenient feature especially in the embodiment of FIG. 1, in which the bottom ram 2 is stationary during press-forming operations. Above the upper ram 1 there is an upper press cylinder space 4a defined by cylinder walls 5 rigidly fixed to the frame 3. The press cylinder space 4a is defined by a vertically reciprocating piston 6a, which, in executing upward and downward movements, reduces or increases the volume of the press cylinder space, with the piston bearing against the upper ram 1 when moved downwards. Above the ram 1 and below the press cylinder space 4a, a return cylinder space 7 is provided which is likewise defined by the cylinder walls 5 rigidly attached to the frame 3. A piston 8 defining the return cylinder space 7, enlarges the volume of this space with any upward movement and reduces it with any downward movement. The piston 8 is rigidly attached to the ram 1. A hammer blow cylinder space 9, which in the example of FIG. 2 is the constituent part of a compression chamber, is defined on the one hand by the piston 8 rigidly fixed to the upper ram 1, and the movement of which piston 8 can be coupled, through the medium of a hydraulic link 10, with a piston 11 rigidly fixed to the bottom ram 2. The piston 11 can move upwards and downwards and in so doing changes the volume of an additional, lower return cylinder space 12.

The hammer blow cylinder space 9 is located above the ram 1, and the gas, e.g., nitrogen, which it contains applies its pressure to the piston 8 rigidly attached to ram I. Said piston 8 is acted upon on its underside by a pressurized fluid medium, e.g., oil, located in the return cylinder space 7 above the ram 1. An upper stern 20a which projects into the hammer blow cylinder space 9, tenninates at its free end on top of the piston 8 fixed to the ram 1 and is rigidly attached at its other end to the piston 6a defining the press cylinder space 4a above the ram 1.

The return cylinder space 7 above the ram 1 connected via a transfer line 31 belonging to the link 10, to a coupling cylinder space 21 in which a plunger or piston, rigidly connected with the bottom ram 2, can slide. This plunger or piston, in the embodiment of FIG. 1, is identical with the piston 11 rigidly fixed to the bottom ram 2 and defining the bottom return cylinder space 12. In both embodiments, however, the hammer blow cylinder space 9 is-rigidly fixed to the frame 3 and the means 10 linking the rams l, 2, is a positive one.

A supply line 13 carrying pressurized fluid (e.g., oil) from a main pump 14 of the high-pressure axial piston type, extends via a press valve 15 tothe press cylinder space 4a. From the main pump 14, a line 16 goes via a check valve 17 to the bottom return cylinder space 12 which is delimited by the bottom piston 11 rigidly attached to the bottom ram 2. In the hammer blow cylinder space 9, with the rams l, 2 moved apart from one another, the gas is entrapped and highly compressed. An extension valve device is provided, which includes an impact valve 18 and a travel valve 19. The travel valve 19 and the impact valve 18 are, in each case, connected with cylinder spaces which are delimited by the pistons 8, 11 rigidly fixed to the two rams l, 2 and are in fact return cylinder spaces 7, 12. Both the impact valve 18 and the travel valve 19 are connected to one of the two return cylinder spaces 7, 12.

In order to retractthe two rarns l, 2, the press valve 15 is closed so that no pressurized fluid can pass into the press cylinder space 4a. The valve 17, on the other hand, is open and the pump 14 supplies pressurized fluid to the return cylinder space 12 associated with the bottom ram 2 and retracts this ram downwards. The piston 11 rigidly fixed to the bottom ram 2, in so doing displaces fluid via the coupling cylinder space 21 and the link 10, into the return cylinder space 7 associated with the upper ram. The piston 8 rigidly attached to the ram 2, retracts upwards and in so doing compresses the gas in the hammer blow cylinder space 9. When the retracting motion has been completed, the machine is under load and the two rams 1, 2 are biased so that if released they will move towards one another.

In order to produce a ram extension movement of the hammer blow kind, for forging operations, the impact valve 18 is opened, with this valve having a large flow area. The gas compressed in the hammer blow cylinder space or compression chamber 9, forces the piston 8 rigidly attached to the upper ram 1, downwards, and, via the link 10, forces the piston 11 rigidly attached to the bottom ram 2, upwards, fluid being displaced through the impact valve 18 from the corresponding return cylinder space 12. During the hammer blow stroke, additional fluid is continuously supplied to the return cylinder space 12 and the gas holds the (twice) piston 6a, which delimits the top press cylinder space 411, in its topmost position against the stem a, by pressure.

For a press-forming stroke, the press valve 15 and the travel valve 19 are operated, with the press valve 15 being open so that pressurized fluid has access via the line 13 to the press cylinder space. The travel valve 19 is opened as well so that liquids can discharge from the return cylinder space 12. The pressurized fluid entering the press cylinder space 40, forces the piston 6a delimiting this space, downwards and likewise, via the stem 20a, the piston 8 rigidly fixed to the upper ram 1 and hence the ram 1 itself. For a press-forming stroke, the gas in the hammer blow cylinder space 9 is at the pressure required for a hammer blow stroke. During the hammer blow, it is subject only to the pressure fluctuations which stem from change in volume.

In the machine in accordance with FIG. 1, the travel valve 19 is arranged in the link 10 and during a pressforming stroke fluid flows from the return cylinder space 7 associated with the ram 1, to the travel valve. The bottom ram 2 does not move during a press-forming operation but rests upon a fluid cushion in the coupling cylinder space 21 which is shut off by a cock 22. Accordingly,'the press cylinder space 40 is provided only in respect of the upper ram 1. In the machine of FIG. 2, by contrast, a press cylinder space 4b is provided in respect of the bottom ram 2 as well, with this space 4b being located centrally below the bottom ram 2. A piston 6b delimiting the bottom press cylinder space 4b, acts via a bottom stem 20b on the piston 11 which is rigidly fixed to thebottom ram 2. The pressurized areas of the two pistons 6a, 6b delimiting the two press cylinder spaces 4a, 4b, are identical. In a special design in which a particularly heavy bottom ram is used, the piston and cylinder spaces 6b, 4b are larger in the ratio of the masses involved, in order to achieve complete compensation. At the same time, the bottom coupling pistons 21 are made larger than the annular areas 7 of the upper piston. In the event of a hammer blow stroke on the part of the bottom ram 2, the bottom piston 6b, with the bottom stem 20b, remains in the lowered position. The travel valve 19 is connected to the return cylinder space 12 which is supplied with pressurized fluid from the main pump 14. In the machine of FIG. 2, both rams l, 2 have the same weight whereas in the machine of FIG. 1, the bottom ram 2 is heavier than the upper ram 1.

The machines in the drawing also include a cylinder 23a of compressed gas, from which, through a pressure-reducing valve 23b and a stop-cock 23c, and also via a gas manometer 23d and a pressure-relief valve '23e, gas can be introduced into the hammer blow cylinder space 9 in a controlled fashion. A transfer pump 24a pumps pressurized fluid into the coupling line 10 and the return cylinder space 7 of the ram 1, via a check valve 24b and via a controlling transfer valve 24c. The main pump 14, via two pressure-relief valves 25a, 25a", feeds on the one hand via the press valve 15 into the press cylinder spaces 4a, 4b, and on the other hand via the return valve 17 and a subsequent check valve 25b, into a retraction cylinder space 12. In the machine in accordance with FIG. 2, two additional pressure-relief valves 25c, 25c" are so arranged in the line 16 to the retraction cylinder space 12, that they are disposed between the travel valve 19 and the retraction cylinder space 12.

The main pump 14, the transfer pump 24a and a control pump 26a, pump fluid from a reservoir 27, to which it ultimately returns from the press cylinder spaces 4 or the retraction cylinder speces 12. The control pump 26a delivers across a check valve 26b and its delivery is controlled by a hydraulic accumulator 260 with a pressure switch and bleed valve. It feeds a selec-' tion stage control system 28 for the press valve 15 and the retraction valve 17, and also serves a hammer blow safety valve 29 and a hammer blow tripping valve 30. The safety valve 29 provides the system with an excesspressure blow-off facility, and the valve 30 operates the hammer blow valve 18.

I claim:

1. A machine for forming a workpiece between a first ram head and a second ram head, with one ram head being arranged above the other ram head, a frame on which the first and second ram heads are guided for movement toward and away from each other, a positive hydraulic coupling between and for the first and second ram heads, an impact cylinder space for said one ram head, a piston activating said one ram head serving to delimit the impact cylinder space, a pressure medium located within an impact cylinder space working on said piston, a stop valve in said hydraulic coupling located closely adjacent the other ram head, with actuation of the stop valve interrupting the coupling of the first and second ram heads, a conduit communicating with the hydraulic coupling for feeding fluid from a pressure source into the hydraulic coupling, a valve fitted in the hydraulic coupling for releasing the fluid from the coupling, a retraction cylinder space for said other ram head, a further piston for activating said other ram head serving to delimit said retraction cylinder space, and additional press cylinder space provided for said one ram head, an additional piston which activates said one ram head serving to delimit the additional press cylinder space, with pressure fluid being capable of being fed to the press cylinder space from a pressure fluid source, and the valve for releasing fluid from the coupling being connected to a part of the hydraulic coupling located between the stop valve and said one ram head such that when the stop valve is opened and the valve for releasing the fluid is closed, the machine can be driven as a hammer with reverse coupled ram heads, and when the stop valve is closed and the valve for releasing fluid is opened, the machine can be driven as a press, with said one ram head being movable against the movable other ram head when pressure fluid is introduced into the press cylinder space.

2. The machine as claimed in claim 1, in which a pressure chamber which can be closed and which surrounds the impact cylinder space is fllled with compressible gas is compressed to a high pressure when the ram heads are retracted.

3. The machine as claimed in claim 1, in which the bottom ram head is several times heavier than the upper ram head.

4. The machine as claimed in claim 1, in which the impact cylinder space is supplied between a press cylinder space and the ram head co-operating with said pressure cylinder space.

5. The machine as claimed in claim 1, in which the piston delimiting the press cylinder space for said one ram head is movable with respect to the ram head associated with the press cylinder space.

6. The machine as claimed in claim 1, in which the piston delimiting the press cylinder space for said one ram head has a stem extending in its own direction of movement into the impact cylinder space.

7. The machine as claimed in claim 1, in which the pistons for the impact cylinder space, press cylinder space and retraction cylinder space are all movable along straight lines along which they are arranged and disposed centrally with respect to the two ram heads. 

1. A machine for forming a workpiece between a first ram head and a second ram head, with one ram head being arranged above the other ram head, a frame on which the first and second ram heads are guided for movement toward and away from each other, a positive hydraulic coupling between and for the first and second ram heads, an impact cylinder space for said one ram head, a piston activating said one ram head serving to delimit the impact cylinder space, a pressure medium located within an impact cylinder space working on said piston, a stop valve in said hydraulic coupling located closely adjacent the other ram head, with actuation of the stop valve interrupting the coupling of the first and second ram heads, a conduit communicating with the hydraulic coupling for feeding fluid from a pressure source into the hydraulic coupling, a valve fitted in the hydraulic coupling for releasing the fluid from the coupling, a retraction cylinder space for said other ram head, a further piston for activating said other ram head serving to delimit said retraction cylinder space, and additional press cylinder space provided for said one ram head, an additional piston which activates said one ram head serving to delimit the additional press cylinder space, with pressure fluid being capable of being fed to the press cylinder space from a pressure fluid source, and the valve for releasing fluid from the coupling being connected to a part of the hydraulic coupling located between the stop valve and said one ram head such that when the stop valve is opened and the valve for releasing the fluid is closed, the machine can be driven as a hammer with reverse coupled ram heads, and when the stop valve is closed and the valve for releasing fluid is opened, the machine can be driven as a press, with said one ram head being movable against the movable other ram head when pressure fluid is introduced into the press cylinder space.
 2. The machine as claimed in claim 1, in which a pressure chamber which can be closed and which surrounds the impact cylinder space is filled with compressible gas is compressed to a high pressure when the ram heads are retracted.
 3. The machine as claimed in claim 1, in which the bottom ram head is several times heavier than the upper ram head.
 4. The machine as claimed in claim 1, in which the impact cylinder space is supplied between a press cylinder spAce and the ram head co-operating with said pressure cylinder space.
 5. The machine as claimed in claim 1, in which the piston delimiting the press cylinder space for said one ram head is movable with respect to the ram head associated with the press cylinder space.
 6. The machine as claimed in claim 1, in which the piston delimiting the press cylinder space for said one ram head has a stem extending in its own direction of movement into the impact cylinder space.
 7. The machine as claimed in claim 1, in which the pistons for the impact cylinder space, press cylinder space and retraction cylinder space are all movable along straight lines along which they are arranged and disposed centrally with respect to the two ram heads. 